Removal of Organic and Inorganic Pollutants Using CSFe3O4@CeO2 Nanocatalyst via Adsorption–Reduction Catalysis: A Focused Analysis on Methylene Blue

Abstract

The synthesis of an efficient catalytic system with a safe catalysis approach has always been the concern of researchers to eradicate the problems arising due to the discharge of colored pollutants by industries in water bodies. Herein, we synthesized a magnetically separable nanocatalyst, CSFe₃O₄@CeO₂, by co-precipitation of CeO₂ on the surface of magnetic Fe₃O₄ nanoparticles embedded in a chitosan hydrogel matrix. The synthesized catalyst was characterized by different analyses viz. FTIR, XRD, SEM–EDX and TEM. The CSFe₃O₄@CeO₂ exhibited enhanced catalytic activity due to the unique synergism of adsorption and catalytic reduction for the removal of pollutants, namely methylene blue (MB), congo red (CR), and potassium ferricyanide using NaBH₄ as a reducing agent. Further investigations of catalytic efficiency of CSFe₃O₄@CeO₂ were done with MB by varying the catalyst dose, concentrations of MB and NaBH₄. The reduction mechanism of MB to LMB (Leucomethylene blue) was studied and explained through adsorption reduction synergism. The reduction rate of MB in all catalytic experiments was determined by pseudo first-order kinetics. The adsorption isotherm data was best fit to Langmuir isotherm model indicated monolayer adsorption of MB on catalyst surface. The reusability of the catalyst with change in catalytic efficiency were also calculated to determine its economic feasibility.